German-Soviet Nonaggression Pact, also called Nazi-Soviet Nonaggression Pact, German-Soviet Treaty of Nonaggression, Hitler-Stalin Pact, Molotov-Ribbentrop Pact, (August 23, 1939), nonaggression pact between Germany and the Soviet Union that was concluded only a few days before the beginning of World War II and which divided eastern Europe into German and Soviet spheres of influence.

Soviet foreign minister Vyacheslav Molotov, having negotiated the German-Soviet Nonaggression Pact of August 1939, is greeted by German foreign minister Joachim von Ribbentrop and other officials in Berlin. From “The Second World War: Prelude to Conflict” (1963), a documentary by Encyclopædia Britannica Educational Corporation.Encyclopædia Britannica, Inc.

The Soviet Union had been unable to reach a collective-security agreement with Britain and France against Nazi Germany, most notably at the time of the Munich Conference in September 1938. By early 1939 the Soviets faced the prospect of resisting German military expansion in eastern Europe virtually alone, and so they began searching about for a change of policy. On May 3, 1939, Soviet leader Joseph Stalin fired Foreign Minister Maksim Litvinov, who was Jewish and an advocate of collective security, and replaced him with Vyacheslav Mikhaylovich Molotov, who soon began negotiations with the Nazi foreign minister, Joachim von Ribbentrop. The Soviets also kept negotiating with Britain and France, but in the end Stalin chose to reach an agreement with Germany. By doing so he hoped to keep the Soviet Union at peace with Germany and to gain time to build up the Soviet military establishment, which had been badly weakened by the purge of the Red Army officer corps in 1937. The Western democracies’ hesitance in opposing Adolf Hitler, along with Stalin’s own inexplicable personal preference for the Nazis, also played a part in Stalin’s final choice. For his part, Hitler wanted a nonaggression pact with the Soviet Union so that his armies could invade Poland virtually unopposed by a major power, after which Germany could deal with the forces of France and Britain in the west without having to simultaneously fight the Soviet Union on a second front in the east. The end result of the German-Soviet negotiations was the Nonaggression Pact, which was dated August 23 and was signed by Ribbentrop and Molotov in the presence of Stalin, in Moscow.

MolotovEncyclopædia Britannica, Inc.

The terms of the German-Soviet Nonaggression Pact were briefly as follows: the two countries agreed not to attack each other, either independently or in conjunction with other powers; not to support any third power that might attack the other party to the pact; to remain in consultation with each other upon questions touching their common interests; not to join any group of powers directly or indirectly threatening one of the two parties; to solve all differences between the two by negotiation or arbitration. The pact was to last for 10 years, with automatic extension for another 5 years unless either party gave notice to terminate it 1 year before its expiration.

To this public pact of nonaggression was appended a secret protocol, also reached on August 23, 1939, which divided the whole of eastern Europe into German and Soviet spheres of influence. Poland east of the line formed by the Narew, Vistula, and San rivers would fall under the Soviet sphere of influence. The protocol also assigned Lithuania, Latvia, Estonia, and Finland to the Soviet sphere of influence and, further, broached the subject of the separation of Bessarabia from Romania. A secret supplementary protocol (signed September 28, 1939) clarified the Lithuanian borders. The Polish-German border was also determined, and Bessarabia was assigned to the Soviet sphere of influence. In a third secret protocol (signed January 10, 1941, by Count Friedrich Werner von Schulenberg and Molotov), Germany renounced its claims to portions of Lithuania in return for Soviet payment of a sum agreed upon by the two countries.

The public German-Soviet Nonaggression Pact caused consternation in the capitals of Britain and France. After Germany invaded Poland from the west on September 1, 1939, Soviet troops invaded Poland from the east on September 17, meeting the advancing Germans near Brest-Litovsk two days later. The partition of Poland was effected on September 29, at which time the dividing line between German and Soviet territory was changed in Germany’s favour, being moved eastward to the Bug River (i.e., the current Polish-Soviet frontier). The Soviets soon afterward sought to consolidate their sphere of influence as a defensive barrier to renewed German aggression in the east. Accordingly, the Soviet Union attacked Finland on November 30 and forced it in March 1940 to yield the Isthmus of Karelia and make other concessions. The Baltic republics of Latvia, Lithuania, and Estonia were annexed by the Soviet Union and were organized as Soviet republics in August 1940. The Nonaggression Pact became a dead letter on June 22, 1941, when Nazi Germany, after having invaded much of western and central Europe, attacked the Soviet Union without warning in Operation Barbarossa.

The Soviet Union’s borders with Poland and Romania that were established after World War II roughly follow those established by the Nonaggression Pact in 1939–41. Until 1989 the Soviet Union denied the existence of the secret protocols because they were considered evidence of its involuntary annexation of the Baltic states. Soviet leaders were initially unwilling to restore prewar boundaries, but the transformations occurring within the Soviet Union in the early 1990s made it virtually impossible for Soviet leaders to combat declarations of independence from the Baltic states in 1991.